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Your eyeglasses prescription is usually a chart that has two rows, one for your right eye and one for your left, and four columns to notate the correction on the lens to help you see clearly.
SPH or Sphere refers to the amount of spherical error for your eyes. Sphere value goes up and down in quarters (+/- 0.25) and is marked by a (+) or (-). A (-) value usually means that you need correction to help you see things far away, and a (+) value means that you need help seeing things up close (reading), or arms-length (computer screen) range.
CYL or Cylinder describes astigmatism, a refractive error that causes distorted and blurred vision. Cylinder value also goes up and down in quarters (+/- 0.25) and is marked by a (+) or (-). Please note that if you do not have astigmatism, this column will be left blank.
AXIS indicates the orientation of astigmatism, measured in degrees 1 to 180. You’ll only see a number here if there is a value in the Cylinder column.
ADD or NV (Near Vision) is used for multifocal or reading correction, measured in quarters (+0.25). This is the value for the reading portion of a bifocal or a progressive lens. Therefore, the ADD value is always indicated by a positive sign (+).
O.D. refers to the right eye.
O.S. refers to the left eye.